The present invention relates to a reference voltage generating circuit and, more particularly, to a reference voltage generating circuit for applying a reference voltage of 1/2 a power source voltage V.sub.CC to a digit line or the like in a semiconductor memory device.
As shown in FIG. 4, a conventional reference voltage generating circuit comprises a resistor R1 having one terminal connected to the power source terminal of a power source voltage V.sub.CC, a resistor R2 having one terminal connected to the ground terminal of a reference potential, an n-type transistor Q3 having the drain and gate connected to the other terminal of the resistor R1, a p-type transistor Q4 having the drain and gate connected to the other terminal of the resistor R2 and the source connected to the source of the transistor Q3, an n-type transistor Q7 having the drain connected to the power source terminal and the gate connected to the drain and gate of the transistor Q3, and a transistor Q8. The transistor Q8 has the drain connected to the ground terminal, the gate connected to the drain and gate of the transistor Q4, and the source connected to the source of the transistor Q7 and used as the output terminal of a reference voltage V.sub.OUT. A current flows in a path of the resistor R1, the transistors Q3 and Q4, and the resistor R2 and a path of the transistors Q7 and Q8, thereby generating a reference voltage of 1/2 a power source voltage V.sub.CC. The reference voltage is applied to a digit line as a precharge voltage or to a counter electrode of a memory cell.
Since the digit line and the counter electrode of the memory cell are regarded as capacitors each having a large capacitance, a reference voltage need not always be applied to the digit line and the counter electrode. However, the above conventional reference voltage generating circuit has a structure in which a current always flows in the path of the resistors R1 and R2 and the transistors Q3 and Q4 and the path of the transistors Q7 and Q8. Therefore, a power is disadvantageously consumed more than necessary.